1. Field of the Invention
The present invention relates generally to an antenna, and more particularly to a multi-band antenna comprising a PIFA (Planar Inverted-F Antenna) and a monopole antenna.
2. Description of the Prior Art
With the development of wireless communication, more and more portable electronic devices, such as notebooks, install antenna systems for working in a Wireless Local-area Network (WLAN). Transmitting and receiving signals plays an important role in wireless communication process. In recent years, a majority of WLAN bases on Bluetooth technical standard or 802.11 technical standard. Antenna in Bluetooth technical standard is based on 2.4 GHz frequency band, and in 802.11 technical standard is based on 2.4 GHz and 5 GHz. So, an antenna in a notebook mostly works at the above frequency bands at the present time.
However, more and more people dissatisfy their electronic devices only working in an immovable network (Signal transmission distance is 10 meters in Bluetooth which almost doesn't permit the electronic devices to move.) or a only short-haul movable network (Signal transmission distance is 150 meters of 802.11 technical standard which limits the movement of the electronic device except between work rooms.) of the WLAN. Making the portable electronic devices working in WWAN (Wireless Wide Area) or GPS (Global Positioning System) is a purpose of the many people. Because the portable electronic devices can work or amuse in broaden range in WWAN or GPS. In recent years, WWAN adopts two newly presented technical standards, GSM and CDMA. Operating frequency bands of the GSM and CDMA are 900/1800 MHz, and operating frequency band of the GPS is 1.575 GHz. So, an antenna of a notebook must operate in above frequency bands, the portable electronic device is capable of working in WWAN or GPS. Taiwan patent No. I220581 discloses a PIFA antenna working in 900/1800 MHz. However, the PIFA antenna has relatively big size in height direction. So, many notebooks or other portable electronic devices do not have enough space to install such PIFA antenna. Further more, said PIFA antenna has narrow band and has disturbance between low frequency and high frequency thereof.
Hence, in this art, a multi-band antenna to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiment.